Unit Converter
Convert between different units
About Unit Converter
Unit Converter is a free online tool that converts between measurement units across all major categories — length, weight, temperature, volume, area, speed, time, energy, pressure, and data storage. Select your input unit, enter a value, select the output unit, and get the converted result instantly.
The world uses two primary measurement systems: the Imperial system (used in the United States, and partially in the UK and Canada) and the International System of Units (SI), also called the metric system (used by most of the world). The coexistence of these systems creates constant conversion needs — recipes, construction measurements, scientific data, international shipping, and medical dosages all require converting between units regularly.
Length conversions are among the most common: inches to centimetres, feet to metres, miles to kilometres. 1 inch = 2.54 cm exactly; 1 mile = 1.60934 km. Weight conversions are also frequent: pounds to kilograms (1 lb = 0.453592 kg), ounces to grams (1 oz = 28.3495 g). Temperature conversions follow different formulas: Celsius to Fahrenheit is (°C × 9/5) + 32; Fahrenheit to Celsius is (°F − 32) × 5/9.
Digital storage units follow a binary or decimal progression depending on context. In computing, 1 kilobyte (KB) is technically 1,024 bytes (2¹⁰), but in storage marketing and SI notation, 1 KB = 1,000 bytes. This causes the common confusion of why a "1 TB" hard drive shows as ~931 GB in the operating system — the drive is marketed in decimal (10¹²) but the OS reports in binary (2⁴⁰). This tool clarifies these distinctions.
How to Use Unit Converter
- 1Select the measurement category (length, weight, temperature, etc.)
- 2Enter the value you want to convert
- 3Select the source unit and the target unit
- 4The converted value is shown instantly
Frequently Asked Questions
Multiply by 9/5 (or 1.8) then add 32. Example: 25°C = (25 × 1.8) + 32 = 45 + 32 = 77°F. A quick mental estimate: double the Celsius value and add 30 (not exact but close for everyday use).
Exactly 2.54 centimetres. This is a defined, exact conversion — 1 inch ≡ 2.54 cm by international agreement since 1959.
Mass (measured in kilograms or pounds-mass) is the amount of matter in an object and is constant regardless of location. Weight is the force of gravity on that mass (measured in Newtons) and varies by gravitational field. In everyday usage, "weight" and "mass" are used interchangeably.
A fluid ounce (fl oz) is a unit of volume. A weight ounce (oz) is a unit of mass. They are different measurements — 1 fl oz of water weighs approximately 1 oz, but 1 fl oz of oil weighs less than 1 oz. Never confuse them in cooking or chemistry.
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